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[LV] Refactor the validation of PHI inductions. NFC

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This moves the validation of PHI inductions into a
separate method, making it easier to reuse this
logic.

llvm-svn: 268632
This commit is contained in:
Silviu Baranga 2016-05-05 15:14:01 +00:00
parent 49bc30f7bb
commit 6de5dd17a2
1 changed files with 48 additions and 29 deletions
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77
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -1406,6 +1406,14 @@ private:
/// invariant.
void collectStridedAccess(Value *LoadOrStoreInst);
/// \brief Returns true if we can vectorize using this PHI node as an
/// induction.
///
/// Updates the vectorization state by adding \p Phi to the inductions list.
/// This can set \p Phi as the main induction of the loop if \p Phi is a
/// better choice for the main induction than the existing one.
bool addInductionPhi(PHINode *Phi, InductionDescriptor ID);
/// Report an analysis message to assist the user in diagnosing loops that are
/// not vectorized. These are handled as LoopAccessReport rather than
/// VectorizationReport because the << operator of VectorizationReport returns
@ -4575,6 +4583,45 @@ static bool hasOutsideLoopUser(const Loop *TheLoop, Instruction *Inst,
return false;
}
bool LoopVectorizationLegality::addInductionPhi(PHINode *Phi,
InductionDescriptor ID) {
Inductions[Phi] = ID;
Type *PhiTy = Phi->getType();
const DataLayout &DL = Phi->getModule()->getDataLayout();
// Get the widest type.
if (!WidestIndTy)
WidestIndTy = convertPointerToIntegerType(DL, PhiTy);
else
WidestIndTy = getWiderType(DL, PhiTy, WidestIndTy);
// Int inductions are special because we only allow one IV.
if (ID.getKind() == InductionDescriptor::IK_IntInduction &&
ID.getStepValue()->isOne() &&
isa<Constant>(ID.getStartValue()) &&
cast<Constant>(ID.getStartValue())->isNullValue()) {
// Use the phi node with the widest type as induction. Use the last
// one if there are multiple (no good reason for doing this other
// than it is expedient). We've checked that it begins at zero and
// steps by one, so this is a canonical induction variable.
if (!Induction || PhiTy == WidestIndTy)
Induction = Phi;
}
DEBUG(dbgs() << "LV: Found an induction variable.\n");
// Until we explicitly handle the case of an induction variable with
// an outside loop user we have to give up vectorizing this loop.
if (hasOutsideLoopUser(TheLoop, Phi, AllowedExit)) {
emitAnalysis(VectorizationReport(Phi) <<
"use of induction value outside of the "
"loop is not handled by vectorizer");
return false;
}
return true;
}
bool LoopVectorizationLegality::canVectorizeInstrs() {
BasicBlock *Header = TheLoop->getHeader();
@ -4628,36 +4675,8 @@ bool LoopVectorizationLegality::canVectorizeInstrs() {
InductionDescriptor ID;
if (InductionDescriptor::isInductionPHI(Phi, PSE.getSE(), ID)) {
Inductions[Phi] = ID;
// Get the widest type.
if (!WidestIndTy)
WidestIndTy = convertPointerToIntegerType(DL, PhiTy);
else
WidestIndTy = getWiderType(DL, PhiTy, WidestIndTy);
// Int inductions are special because we only allow one IV.
if (ID.getKind() == InductionDescriptor::IK_IntInduction &&
ID.getStepValue()->isOne() && isa<Constant>(ID.getStartValue()) &&
cast<Constant>(ID.getStartValue())->isNullValue()) {
// Use the phi node with the widest type as induction. Use the last
// one if there are multiple (no good reason for doing this other
// than it is expedient). We've checked that it begins at zero and
// steps by one, so this is a canonical induction variable.
if (!Induction || PhiTy == WidestIndTy)
Induction = Phi;
}
DEBUG(dbgs() << "LV: Found an induction variable.\n");
// Until we explicitly handle the case of an induction variable with
// an outside loop user we have to give up vectorizing this loop.
if (hasOutsideLoopUser(TheLoop, &*it, AllowedExit)) {
emitAnalysis(VectorizationReport(&*it)
<< "use of induction value outside of the "
"loop is not handled by vectorizer");
if (!addInductionPhi(Phi, ID))
return false;
}
continue;
}